JP6020752B1 - Diagnostic equipment - Google Patents

Abstract

An object of the present invention is to reduce the influence of noise in controlling a rotating machine. A diagnostic tool for performing a diagnosis of a cutting tool included in a rotating machine or the rotating machine based on electric power supplied to the rotating machine measures the power, and inputs the power measuring unit and the power measuring unit. The above-mentioned problem is solved by filtering noise that enters from the output side. [Selection] Figure 8

Description

  The present invention relates to a diagnostic apparatus.

  Machine tools using a motor or the like are known. And the following methods of detecting an abnormality of a motor of a machine tool are known.

  First, in a machine tool, electric power supplied to a motor that periodically drives an operation unit is measured, and data of electric power measured for each drive cycle period of the operation unit is stored. Next, the rate of change between the current power data and the previous stored power data is calculated, and an abnormality in the operating unit is detected based on the calculated rate of change. Thus, a method for detecting an abnormality in the power supplied to the motor is known (for example, Patent Document 1).

Japanese Patent No. 3783191

  However, the conventional method may be affected by noise in the control of the rotating machine.

  One aspect of the present invention has been made in view of such a problem, and an object thereof is to reduce the influence of noise in control of a rotating machine or the like.

In order to solve the above-described problems and achieve the object, a diagnostic device for performing a diagnosis of a cutting tool included in a rotating machine or the rotating machine based on electric power supplied to the rotating machine,
A power measuring unit for measuring the power;
A filter unit that filters noise entering from the input side of the power measurement unit and the output side of the power measurement unit;
The power measuring unit includes a Hall element, and an applied voltage of a power supply line that supplies the power to the rotating machine from an inverter or a servo amplifier is input to the Hall element.
A Hall current is caused to flow through the Hall element based on the applied voltage, and a magnetic flux proportional to the applied current to the rotating machine is applied to the sensor surface of the Hall element, and the product of the magnetic flux and the Hall current is generated. The power is calculated based on the proportional Hall voltage.

  According to the present invention, the influence of noise can be reduced in the control of a rotating machine and the like.

It is a conceptual diagram which shows an example of the whole structure using the diagnostic apparatus in one Embodiment of this invention. It is a block diagram which shows the structure of the electric power measurement part and filter part which the diagnostic apparatus in one Embodiment of this invention has. It is a figure which shows an example of the integrating circuit which the diagnostic apparatus in one Embodiment of this invention has. It is a figure which shows an example of the diagnosis using the electric power calculation signal in one Embodiment of this invention. It is a figure which shows an example of another diagnosis using the electric power calculation signal in one Embodiment of this invention. It is a circuit diagram which shows an example of the equivalent circuit of the electric power measurement part and filter part which the diagnostic apparatus in one Embodiment of this invention has. It is a figure which shows an example of the magnetic flux collection core which the diagnostic apparatus in one Embodiment of this invention has. It is a functional block diagram which shows an example of a function structure of the diagnostic apparatus in one Embodiment of this invention. It is a conceptual diagram which shows an example of the whole structure using the diagnostic apparatus of a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1. Example of overall configuration Functional configuration example of diagnostic device ≪ 1. Overall configuration example ≫
FIG. 1 is a conceptual diagram showing an example of the overall configuration using a diagnostic apparatus according to an embodiment of the present invention. For example, the diagnostic device 1 is used in a configuration as illustrated. Specifically, the illustrated configuration is a configuration in which power is supplied from the inverter INV to the motor M, which is an example of a rotating machine, via a power supply line LP, which is an example of a power supply unit. Hereinafter, the configuration shown in the figure will be described as an example.

  The motor M rotates a cutting tool CT such as a milling cutter or a drill attached by the cutting tool attaching jig JG. Then, when the rotating processing blade CT comes into contact with a workpiece such as metal, the processing blade CT performs processing in which the workpiece is cut or a hole is made. In this way, the motor M uses the power supplied from the inverter INV, the servo amplifier, or the like to rotate the machining tool CT to process the workpiece.

  Further, the motor M may fix the work with a jig or the like that the motor M has and rotate the work. In this case, the machining tool CT is applied to the rotating workpiece, and the workpiece is machined.

  A controller CTL such as a PLC (Programmable Logic Controller) is connected to the inverter INV. The controller CTL controls the inverter INV, the servo amplifier, or the like by the control signal SIGC. Specifically, the controller CTL performs speed control for controlling the rotational speed of the motor M, position control for controlling the position of the motor M, and the like. Further, the controller CTL has a diagnosis unit DI. As illustrated, the diagnosis unit DI performs diagnosis of the motor M or the processing blade CT based on the power calculation signal SIGD and the like. Details of the diagnosis will be described later.

  In the illustrated example, the diagnostic apparatus 1 is connected to the power supply line LP. Specifically, the diagnostic apparatus 1 is connected to a power supply line LP by attaching a power sensor SP that is an example of a power measuring unit. Note that the power sensor SP has, for example, a Hall element. Further, the power sensor SP takes in the voltage signal SIGV indicating the applied voltage on the power supply line LP. Details of the power sensor SP will be described later. Then, the addition computing unit CO is connected to each power sensor SP, which is an example of a power measuring unit, through a signal line, and adds each power measured by the power sensor SP. Specifically, as shown in the figure, in the case of a three-phase motor M, the addition computing unit CO adds three electric powers.

  FIG. 2 is a block diagram illustrating configurations of a power measurement unit and a filter unit included in the diagnostic device according to the embodiment of the present invention. As illustrated, the power sensor SP includes an integrating circuit IN and an amplifier circuit AP. Further, the diagnostic device is, for example, as an example of a filter unit, as illustrated, and a first filter FL1 disposed on the input side, and a second filter FL2 disposed on the output side, which is an example of the filter unit. Have In addition to the first filter FL1 and the second filter FL2, the addition computing unit CO (see FIG. 1) may further include a filter.

  The integrating circuit IN is realized by, for example, a Hall element. Specifically, the integration circuit IN is, for example, the following circuit.

  FIG. 3 is a diagram illustrating an example of an integration circuit included in the diagnostic device according to the embodiment of the present invention. As in the illustrated example, the integrating circuit IN is configured using a Hall element HE that detects magnetism. That is, the integrating circuit IN calculates power by so-called Hall multiplication.

  Specifically, first, the integrating circuit IN is proportional to the applied voltage of power supplied by the power supply line LP (see FIG. 1) between the input terminals of the Hall element HE, that is, the voltage indicated by the voltage signal SIGV. A current (hereinafter referred to as “Hall current Ic”) is passed.

  Next, as shown in the figure, the integrating circuit IN is proportional to the applied current of the power supplied by the power supply line LP to the sensor surface of the Hall element HE, that is, the applied current to the motor M (see FIG. 1). Magnetic flux B is applied. In this way, a voltage proportional to the product of the magnetic flux B and the hall current Ic (hereinafter referred to as “Hall voltage Vh”) is generated at the output terminal of the integrating circuit IN. Then, the integration circuit IN outputs a signal indicating the Hall voltage Vh to the amplifier circuit AP (see FIG. 2).

  Returning to FIG. 2, the amplifier circuit AP amplifies the signal indicating the Hall voltage Vh and generates a signal indicating power (hereinafter referred to as “power signal SIGP”). In other words, the amplifier circuit AP amplifies the input signal so as to have a predetermined voltage level.

  Then, the diagnostic device adds the respective powers indicated by the three power signals SIGP in the three phases, that is, in the three phases. Next, the diagnosis apparatus transmits a result of the addition, that is, a power calculation signal SIGD or the like indicating the power supplied to the motor M (see FIG. 1) or the like to the controller CTL or the like. The controller CTL may perform various controls based on the power calculation signal SIGD. In addition, for example, the following diagnosis is performed using the power calculation signal SIGD.

  FIG. 4 is a diagram illustrating an example of diagnosis using a power calculation signal according to an embodiment of the present invention. In the graph shown in the figure, the power calculation signal SIGD (see FIG. 1) adds the power signal SIGP of each phase, that is, the power supplied to the motor M (see FIG. 1) (indicated by the vertical axis in the figure). Is a time series (indicated by a horizontal axis in the figure) of the value indicated by the signal. As shown in the figure, when the processing time elapses, the power increases due to the consumption of the blade. Therefore, based on whether or not the power is equal to or higher than a predetermined value set in advance, the diagnostic device can diagnose whether or not the cutting tool is in a worn state. In addition, the diagnostic device can perform, for example, the following diagnosis based on the power calculation signal SIGD.

  FIG. 5 is a diagram illustrating an example of another diagnosis using the power calculation signal according to the embodiment of the present invention. As in FIG. 4, the graph shown in FIG. 4 is a result of adding the power signal SIGP of each phase to the power calculation signal SIGD (see FIG. 1), that is, power supplied to the motor M (see FIG. 1). In this case, the value indicated by the signal is shown in a time series (indicated by the horizontal axis in the figure). For example, when a part of the cutting tool is chipped for some reason, the cutting tool may be caught on the workpiece during processing. Therefore, when there is such a catch, as shown in the figure, the value indicated by the power calculation signal SIGD becomes higher corresponding to a portion where the cutting tool is periodically missing. Therefore, when a waveform as shown in the figure is observed, the diagnostic device can diagnose that a part of the blade is damaged or the like. In many cases, the waveform as shown in the figure is periodically observed every rotation of the blade. Therefore, it is desirable to measure the power at high speed.

  Hereinafter, an example in which the motor M (see FIG. 1) rotates the blade at 3600 rpm (revolution per minute), that is, 60 rps (revolutions per second) will be described. In this example, one rotation is about “1/60 rps = 16.666... Msec≈15 msec” (hereinafter, one rotation is assumed to be 15 msec).

  Furthermore, in this example, for example, it is assumed that there is a 5 ° blade damage. That is, it is assumed that a portion of “5 ° / 360 ° = 1/72” is damaged in one rotation and 360 ° of the blade. In this case, the waveform indicating the damaged portion has a pulse width of about “15 msec × (1/72) = 0.208333... Msec = 208.333... Μsec≈200 μsec” (hereinafter, the damaged portion Is assumed to have a pulse width of 200 μsec). And in order to measure such a waveform, a diagnostic apparatus measures with the resolution | decomposability of about [1/2] or less of the measured pulse width based on the sampling theorem. The resolution is preferably about [1/5] or less of the measured pulse width. More preferably, the resolution is about “1/10” or less of the measured pulse width. That is, when measuring a waveform having a pulse width of about “200 μsec”, it is desirable that the diagnostic apparatus has a resolution that can be measured at a speed of about “15 to 20 μsec” or less. Note that the resolution may be determined based on the angle at which the blade to be detected is damaged.

  Thus, when measuring at high speed, as shown in FIG. 2, it is desirable to use a circuit or the like. That is, if it is set as a structure as shown in FIG. 2, the diagnostic apparatus can measure electric power at high speed.

  In addition, the diagnostic device may detect an abnormality of the rotating machine. For example, when the electric power is equal to or higher than a predetermined value set in advance, an abnormality may have occurred in the rotating machine. Specifically, when the rotating machine is caught by something, a large current may flow to generate a large torque to rotate the rotating machine. In such a case, power also increases with current. In this way, the diagnostic device may detect an abnormality of the rotating machine.

  Further, the noises filtered by the first filter FL1 (see FIG. 2) and the second filter FL2 (see FIG. 2) are preferably 60 MHz to 80 MHz noise at 10 V application and 150 MHz to 200 MHz noise at 10 V / m. .

  The voltage signal SIGV (see FIG. 2) or the like is often affected by magnetic noise (sometimes referred to as “electric noise”) generated mainly by the motor M (see FIG. 1) or the like. Furthermore, the voltage signal SIGV or the like is often affected by radio noise generated mainly by the inverter INV (see FIG. 1) or the like. In particular, the influence of noise is likely to increase in a configuration in which the power sensor SP (see FIG. 1), the addition operation unit CO, the motor M, and the inverter INV are arranged close to each other for reasons such as downsizing the machine tool. In addition, when a switching power supply is used, power supply noise due to the switching power supply is also affected. Therefore, if the diagnostic apparatus filters the noise in the frequency band as described above by the input side, that is, the first filter FL1, the diagnostic apparatus can reduce the influence of the noise.

  Further, as shown in FIG. 2, it is desirable that the output side, that is, the second filter FL2 be provided. On the output side, noise is likely to enter from devices connected to the output side. Therefore, if there is the second filter FL2, the diagnostic apparatus can filter noise that enters from the output side, and can reduce the influence of noise.

  If it is set as the structure of the above electric power measurement parts and filter parts, it can show as follows, for example.

  FIG. 6 is a circuit diagram illustrating an example of an equivalent circuit of the power measurement unit and the filter unit included in the diagnostic device according to the embodiment of the present invention. For example, the configuration shown in FIG. 2 can be shown by a circuit diagram as shown.

  First, a voltage indicated by the voltage signal SIGV is input. Next, when a voltage based on the voltage signal SIGV is input, a hall current Ic (see FIG. 3) is generated. Further, when the magnetic flux B proportional to the applied current flowing through the power supply line LP is applied to the Hall element HE, the Hall element HE integrates the magnetic flux B and the Hall current Ic to thereby generate a Hall voltage Vh indicating power (FIG. 3). Reference) can be output. When the signal indicating the Hall voltage Vh is amplified by an amplifier or the like, the diagnostic device can output a power signal SIGP indicating power.

  Furthermore, when there is the first filter FL1, the diagnostic device filters noise that affects the voltage signal SIGV (hereinafter referred to as “first noise NZ1”), and the influence can be reduced. The first noise NZ1 is an example of noise included in the voltage applied to the rotating machine that is input to the power measurement unit. Similarly, when there is the second filter FL2, the diagnostic apparatus filters noise that affects the power signal SIGP (hereinafter referred to as “second noise NZ2”), and the influence can be reduced. The second noise NZ2 is an example of noise that enters from the output side of the power measurement unit. As described above, when the diagnostic device has a filter so as to surround the Hall element HE or the like, the diagnostic device filters various noises such as the first noise NZ1 and the second noise NZ2, and reduces the influence of the noise. be able to.

  In order to generate the magnetic flux B, the diagnostic device preferably has, for example, the following magnetic flux collecting core.

  FIG. 7 is a diagram illustrating an example of a magnetic flux collecting core included in the diagnostic device according to the embodiment of the present invention. As shown in the drawing, the magnetic flux collecting core includes a magnetic material BM such as ferrite or permalloy. And magnetic material BM is installed so that electric wires, such as electric power supply line LP, may be covered so that it may show in figure. Further, the magnetic material BM has a notch, and a hall element HE is installed in the notch as illustrated. When such a magnetic flux collecting core is used, the magnetic flux collecting core serves as a shield, and thus the diagnostic apparatus can reduce the influence of disturbance noise.

≪ 2. Functional configuration example of diagnostic device ≫
FIG. 8 is a functional block diagram illustrating an example of a functional configuration of the diagnostic apparatus according to the embodiment of the present invention. As illustrated, the diagnostic device 1 includes, for example, a power supply unit FN1, a power measurement unit FN2, a filter unit FN3, an addition operation unit FN4, and a diagnosis unit FN5.

  The power supply unit FN1 supplies power to a rotating machine such as the motor M. For example, the power supply unit FN1 is realized by a power supply line LP (see FIG. 1) or the like.

  The power measurement unit FN2 measures the power supplied by the power supply unit FN1. For example, the power measurement unit FN2 is realized by a power sensor SP (see FIG. 1) or the like.

  The filter unit FN3 filters noise included in the input to the power measurement unit FN2 and the output from the power measurement unit FN2. For example, the filter unit FN3 is realized by the first filter FL1 (see FIG. 2), the second filter FL2 (see FIG. 2), and the like.

  The addition calculation unit FN4 calculates the power supplied to the motor M by adding a plurality of measurement results obtained by the power measurement unit FN2. For example, the addition operation unit FN4 is realized by an addition operation unit CO (see FIG. 1) or the like.

  The diagnosis unit FN5 diagnoses the motor M or the cutting tool based on the calculation result calculated by the addition calculation unit FN4, that is, the electric power supplied to the motor M. For example, the diagnosis unit FN5 is realized by a controller CTL (see FIG. 1) or the like.

  As shown in the figure, when the configuration includes the filter unit FN3, the diagnostic apparatus 1 can reduce the influence of noise included in the input to the power measurement unit FN2 and the output from the power measurement unit FN2. For example, a description will be given in comparison with the following comparative example.

  FIG. 9 is a conceptual diagram showing an example of the overall configuration using the diagnostic device of the comparative example. In the comparative example as shown, the current signal line and the voltage signal are easily affected by noise NZ such as magnetic noise or radio noise. For this reason, noise is included in the calculation result by the addition calculator, and accurate diagnosis may be difficult.

  In particular, current sensors often output weak signals. For this reason, since the S / N ratio is poor, the configuration is often particularly vulnerable to noise.

  On the other hand, in the embodiment according to the present invention, the noise such as magnetic noise or radio wave noise can be filtered by the filter unit FN3, and noise entering the power measurement unit FN2 can be reduced. Therefore, the diagnostic apparatus according to the present invention can reduce the influence of noise in the control of a rotating machine and the like. Therefore, since the diagnostic device can detect a small change in power, it can diagnose a small change in the cutting tool. In addition, when the value measured by the power sensor SP (see FIG. 1) is used, the power can be calculated with higher accuracy than when the value measured by the current sensor is used.

  The machine tool having the diagnostic device is, for example, a milling machine, a drilling machine, or an NC (Numerical Control) machine. In addition, the machine tool may be a lathe or the like.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-described embodiments, and various modifications or changes can be made within the scope of the gist of the present invention described in the claims. Is possible.

DESCRIPTION OF SYMBOLS 1 Diagnostic apparatus M Motor SP Electric power sensor SIGV Voltage signal SIGP Electric power signal FL1 1st filter FL2 2nd filter HE Hall element B Magnetic flux FN1 Electric power supply part FN2 Electric power measurement part FN3 Filter part FN4 Addition operation part FN5 Diagnosis part

Claims (8)

A diagnostic device for performing a diagnosis of a cutting tool included in a rotating machine or electric power supplied to the rotating machine,
A power measuring unit for measuring the power;
A filter unit that filters noise entering from the input side of the power measurement unit and the output side of the power measurement unit;
The power measuring unit includes a Hall element, and an applied voltage of a power supply line that supplies the power to the rotating machine from an inverter or a servo amplifier is input to the Hall element.
A Hall current is caused to flow through the Hall element based on the applied voltage, and a magnetic flux proportional to the applied current to the rotating machine is applied to the sensor surface of the Hall element, and the product of the magnetic flux and the Hall current is generated. A diagnostic device that calculates the power based on a proportional Hall voltage. The filter unit is
A first filter for filtering noise included in the applied voltage;
The diagnostic apparatus according to claim 1, further comprising: a second filter that is disposed on an output side of the power measurement unit and filters noise entering from the output side.   The diagnostic apparatus according to claim 2, wherein the first filter is connected to an input signal line of the Hall element, and the second filter is connected to an output signal line of the Hall element.   The diagnostic apparatus according to claim 1, wherein a magnetic flux collecting core is used to generate the applied current.   The diagnostic device according to any one of claims 1 to 4, wherein the filter unit filters the noise of 60 to 80 MHz and 150 MHz to 200 MHz.   The diagnostic device according to claim 1, wherein the rotating machine is a motor and rotates the blade.   The diagnostic apparatus according to claim 1, wherein the power measurement unit has a resolution of 20 μsec or less. Including a plurality of the power measuring units,
The diagnostic apparatus according to any one of claims 1 to 7, further comprising an addition calculator that adds the outputs from the power measurement unit and adds the electric power input to the rotating machine.

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